1. Field of the Invention
The present invention relates to a nacelle and wing combination for an aircraft, and more specifically to a nacelle and wing combination where the nacelle can be mounted closely to the wing with a relatively low nacelle installation drag.
2. Background Art
Most recent designs for large jet powered subsonic aircraft have pod-mounted engines located beneath the wing. It is desirable to mount these engines as closely as possible to the wing lower surface in order to minimize the structural weight and wetted area of the strut supporting the engine. Another significant advantage in mounting the engines more closely to the wing is that this permits reducing the length of the landing gear necessary to keep the engines sufficiently far from the ground. However, if the engines are mounted too closely to the wing, aerodynamic interference can occur between the wing, the engine nacelle, and the strut that supports the engine.
A search of the patent literature has revealed a number of U.S. patents. These are noted below.
U.S. Pat. No. 4,314,681, Kutney, discusses the problem of aerodynamic drag that is created by mounting an engine nacelle to a wing. To alleviate this problem, the patent describes a design where there is an add-on fairing to produce certain desired aerodynamic effects. In one arrangement, the contour of the pylon is modified. In another arrangement, there is provided a "bump" at the intersection of the wing and the pylon.
U.S. Pat. No. 3,533,237, Ravone, also addresses the problem of nacelle installation drag. This patent describes a nacelle configuration which is characterized by external wall surfaces which converge in a downstream direction at small angles.
U.S. Pat. No. 3,952,971, Whitcomb, relates generally to a wing configuration where there is described certain desired lower surface pressure distributions where the flow at the lower surface accelerates rapidly to a high subsonic velocity in the forward half of the airfoil. This patent does not deal directly with the problem of nacelle installation drag.
U.S. Pat. No. 4,524,928--Schmidt, shows a wing configuration where there is a pressure distribution pattern over the lower surface where the flow at the lower surface accelerates rapidly to a high velocity in the first 10 percent to 15 percent of the chord length of the airfoil. This does not deal directly with the problem of nacelle installation drag.
U.S. Pat. No. 4,489,905--Bengelink et al, shows a wing mounted pylon having a sharp edge portion to develop a desired vortex adjacent to the pylon.
A number of other patents which were disclosed in the search appear to be no more relevant, and quite likely less relevant, than the patents noted above. Accordingly, these are being listed without any discussion of the same: U.S. Pat. No. 2,488,991, Stalker; U.S. Pat. No. 2,968,209, Kerry; U.S. Pat. No. 3,129,906, Peterson; U.S. Pat. No. 3,199,813, Roper; U.S. Pat. No. 3.614,028, Kleckner; U.S. Pat. No. 3,744,745, Kerker; U.S. Pat. No. 3,960,345, Lippert, Jr.; U.S. Pat. No. 4,050,651, Neal; U.S. Pat. No. 4,171,786, Krenz; U.S. Pat. No. 4,311,289, Finch; and U.S. Pat. No. 4,318,516, Cole.